Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is fully covered without prose. The description contributes genuinely useful context by sketching the shape of each returned country record (treaty title, dates, link, tax burden data), which matters because no output schema exists, but it says nothing about result size, ordering, or pagination. That is a modest but real addition beyond the structured fields.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

It is a single front-loaded sentence opening with the verb and resource, with no filler or repetition of the title. The colon-and-list construction becomes clause-heavy toward the end ('whether ... whether ... plus ...'), which costs a little readability for an agent parsing constraints, but no sentence is wasted.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a one-parameter, read-only lookup with no output schema, the description is close to sufficient: it names the returned data categories and links the result to downstream check_residency use. It leaves gaps around result cardinality and whether all countries are returned or filtered by the version's home state rules, which an agent might want before calling.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and the single enum parameter is documented in-schema, including the 'Version id from list_versions' provenance hint, so the baseline is 3. The description reinforces the parameter's role by explaining that the version determines the 'home state' against which countries are checked, adding light semantic framing rather than new syntax or format detail.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description gives a specific verb and resource ('Lists the countries') scoped to a version's home state, and enumerates the payload (treaty status with title/dates/link, per-income rules and tax burden data, citizenship options). This is clearly distinct from list_versions or compare_business_forms. It stops short of an explicit 'not this, use X instead' contrast, but the content scoping does most of the differentiating work.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied rather than stated: an agent can infer this is the discovery step before check_residency, since the description ties the returned citizenship options and years to that tool. There is no explicit when-to-use/when-not framing, no mention of prerequisites beyond the version id, and no named alternative for lookup of a single country.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.